1. Field of the Invention
The present invention relates to a connection structure for a battery module, a battery module and a method of connecting terminals of battery modules.
2. Discussion of the Background
A nickel hydrogen battery, a lithium ion battery, etc., which are used as power supplies for drive motors in electric vehicles, hybrid vehicles and the like, are designed to provide large power with the use of a battery pack having cells connected in series. Such a battery pack is called “battery module”.
To provide greater power, battery modules are connected in series. The battery modules are electrically connected by using connecting parts called “intermodule bus bars”. The intermodule bus bar is connected to an intermodule connector provided on a battery module to be connected to the battery module.
Japanese Unexamined Patent Application Publication No. 2009-289431 discloses a power supply control device for a battery pack (battery module), which facilitates bus bar wiring by achieving the optimal arrangement of battery modules and can be made compact as a whole.
According to the technique described in Japanese Unexamined Patent Application Publication No. 2009-289431, since the intermodule bus bar is exposed, short-circuiting may undesirably occur between battery modules or in a battery module when a metallic object such as a tool drops and contacts connecting portions between two battery modules at the time of assembling.
Further, according to the technique described in Japanese Unexamined Patent Application Publication No. 2009-289431, the order of mounting intermodule bus bars, a module cover, and so forth is determined, so that when the components are attached once, some component may not be replaced unless all the components are detached. This results in an increase in the number of assembling steps when wrong wiring is made, for example.
FIGS. 6A to 6C show examples of connection of a general battery module. FIG. 6A shows an example of correct connection of a battery module 1, and FIGS. 6B and 6C show examples of wrong connection of the battery module 1.
In FIGS. 6A to 6C, white circles indicate negative (−) terminals, and black solid circles indicate positive (+) terminals. Broken-line arrows indicate the directions of current.
Since the negative terminals and the positive terminals are alternately connected by intermodule bus bars 300a to 300c in FIG. 6A, individual battery modules 1a to 1d are connected in series correctly.
In the wrong connection in FIG. 6B, when the negative terminal of the battery module 1a is connected to the positive terminal of the battery module 1b by an intermodule bus bar 300d or a tool or the like, short-circuiting occurs between the battery module 1a and the battery module 1b. 
In the wrong connection in FIG. 6C, when the negative terminal of the battery module 1c is connected to the positive terminal of the battery module 1d by an intermodule bus bar 300e, short-circuiting occurs between the battery module 1c and the battery module 1d. 